Extendible stent apparatus

ABSTRACT

The present invention concerns novel stent apparatuses for use in treating lesions at or near the bifurcation point in bifurcated cardiac, coronary, renal, peripheral vascular, gastrointestinal, pulmonary, urinary and neurovascular vessels and brain.vessels. More particularly, the invention concerns a stent apparatus with at least one side opening which may further comprise an extendable stent portion laterally extending from the side opening and at least partly in registry with the wall of the side opening. Devices constructed in accordance with the invention include, singularly or in combination, a main expandable stent comprising at least one substantially circular side opening located between its proximal and distal end openings, which side opening may further comprise an expandable portion extending radially outward from the edges of the side opening; and a branch stent comprising proximal and distal end openings and which may further comprise a contacting portion at its proximal end, and which may optionally be constructed to form either a perpendicular branch or a non-perpendicular branch when inserted through a side opening of the main stent. The stents of the invention are marked with, or at least partially constructed of, a material which is imageable during intraluminal catheterization techniques, most preferably but not limited to ultrasound and x-ray.

RELATED APPLICATIONS

[0001] This Application is a continuation-in-part of U.S. patentapplication Ser. No. 08/744,002, filed on Nov. 4, 1996.

BACKGROUND

[0002] A type of endoprosthesis device, commonly referred to as a stent,may be placed or implanted within a vein, artery or other tubular bodyorgan for treating occlusions, stenoses, or aneurysms of a vessel byreinforcing the wall of the vessel or by expanding the vessel. Stentshave been used to treat dissections in blood vessel walls caused byballoon angioplasty of the coronary arteries as well as peripheralarteries and to improve angioplasty results by preventing elastic recoiland remodeling of the vessel wall. Two randomized multicenter trialshave recently shown a lower restenosis rate in stent treated coronaryarteries compared with balloon angioplasty alone (Serruys, P W et. al.New England Journal of Medicine 331: 489-495, 1994, Fischman, DL et. al.New England Journal of Medicine 331: 496-501, 1994). Stents have beensuccessfully implanted in the urinary tract, the bile duct, theesophagus and the tracheo-bronchial tree to reinforce those body organs,as well as implanted into the neurovascular, peripheral vascular,coronary, cardiac, and renal systems, among others. The term “stent” asused in this application is a device which is intraluminally implantedwithin bodily vessels to reinforce collapsing, dissected, partiallyoccluded, weakened, diseased or abnormally dilated or small segments ofa vessel wall.

[0003] One of the drawbacks of conventional stents is that they aregenerally produced in a straight tubular configuration. The use of suchstents to treat diseased vessels at or near a bifurcation (branch point)of a vessel may create a risk of compromising the degree of patency ofthe primary vessel and/or its branches, or the bifurcation point andalso limits the ability to insert a second stent into the side branch ifthe result of treatment of the primary, or main, vessel is suboptimal.Suboptimal results may occur as a result of several mechanisms, such asdisplacing diseased tissue, plaque shifting, vessel spasm, dissectionwith or without intimal flaps, thrombosis, and embolism.

[0004] The risk of branch compromise is increased generally in twoanatomical situations. First, a side branch may be compromised whenthere is a stenosis in the origin of the side branch. Second, when thereis an eccentric lesion at the bifurcation site, asymmetric expansion cancause either plaque shifting or dissection at the side branch origin.There are reports of attempts to solve this problem by inserting aballoon into the side branch through the struts of a stent deployed inthe main branch spanning the bifurcation point; however, this techniquecarries the risk of balloon entrapment and other major complications(Nakamura, S. et al., Catheterization and Cardiovascular Diagnosis 34:353-361 (1995)). Moreover, adequate dilation of the side branch islimited by elastic recoil of the origin of the side branch. In addition,insertion of a traditional stent into a main vessel spanning a thebifurcation point may pose a limitation to blood flow and access to theside branch vessel. The term “stent jail” is often used to describe thisconcept. In this regard, the tubular slotted hinged design of thePalmaz-Schatz intracoronary stent, in particular, is felt to beunfavorable for lesions with a large side branch and is generallybelieved to pose a higher risk of side branch vessel entrapment wherethe stent prevents or limits access to the side branch. Id.

[0005] One common procedure for intraluminally implanting a stent is tofirst open the relevant region of the vessel with a balloon catheter andthen place the stent in a position that bridges the treated portion ofthe vessel in order to prevent elastic recoil and restenosis of thatsegment. The angioplasty of the bifurcation lesion has traditionallybeen performed using the “kissing” balloon technique where twoguidewires and two balloons are inserted, one into the main branch andthe other into the side branch Stent placement in this situationrequires the removal of the guidewire from the side branch andreinsertion through the stent struts, followed by the insertion of aballoon through the struts of the stent along the guidewire. The firstremoval of the guidewire poses the risk of occlusion of the side branchduring the deployment of the stent in the main branch.

[0006] Prior art patents refer to the construction and design of boththe stent as well as the apparatus for positioning the stent within thevessel. One representative patent to Chaudhury, U.S. Pat. No. 4,140,126,discloses a technique for positioning an elongated cylindrical stent ata region of an aneurysm to avoid catastrophic failure of the bloodvessel wall. The '126 patent discloses a cylinder that expands to itsimplanted configuration after insertion with the aid of a catheter.Dotter, U.S. Pat. No. 4,503,569, discloses a spring stent which expandsto an implanted configuration with a change in temperature. The springstent is implanted in a coiled orientation and is then heated to causethe spring to expand. Palmaz, U.S. Pat. No. 4,733,665, discloses anumber of stent configurations for implantation with the aid of acatheter. The catheter includes a mechanism for mounting and retaining astent, preferably on an inflatable portion of the catheter. The stentsare implanted while imaged on a monitor. Once the stent is properlypositioned, the catheter is expanded and the stent separated from thecatheter body. The catheter can then be withdrawn from the subject,leaving the stent in place within the blood vessel. Palmaz, U.S. Pat.No. 4,739,762, discloses an expandable intraluminal graft. Schjeldahlet. al., U.S. Pat. No. 4,413,989, discloses a variety of ballooncatheter constructions. Maginot, U.S. Pat. No. 5,456,712 and Maginot,U.S. Pat. No. 5,304,220 disclose a graft and stent assembly and a methodof implantation where a stent is used to reinforce a graft that issurgically inserted into a blood vessel in order to bypass an occlusion.However, none of these patents relate to stents which are structurallyadapted for the treatment of bifurcation lesions, or disclose abifurcating stent apparatus.

[0007] Taheri, U.S. Pat. No. 4,872,874, Piplani et. al., U.S. Pat. No.5,489,295, and Marin et al., U.S. Pat. No. 5,507,769, disclosebifurcating graft material which may be implanted using stents asanchors for the graft. However, bifurcated stents are not taught ordisclosed, and the purpose of the stent as used in these inventions issimply to anchor the graft into the vessel wall. It does not reinforcethe vessel wall, treat a lesion, or prevent restenosis afterangioplasty.

[0008] MacGregor, U.S. Pat. No. 4,994,071, discloses a hingedbifurcating stent. In the 071′ patent, in contrast to the presentinvention, there is a main stent with two additional stents attached atone end of the main stent, creating a single unit with a trunk attachedat an end to two smaller stents. The two additional stents arepermanently attached to the end of the trunk (and not the side, as inthe present invention) and cannot be removed from the main stent. Thus,this invention may not be used to treat only one branch of a bifurcatedvessel, is not appropriate for use when the branch vessel extendslaterally from the side of a main vessel (as opposed to an end of a mainvessel), and does not cover the origin of a bifurcated vessel orbifurcation lesion. In addition, studies with hinge-containing stentshave shown that there is a high incidence of restenosis (tissue growth)at the hinge point that may cause narrowing or total occlusion of thevessel and thus compromise blood flow. Furthermore, this design has arelatively large size as compared to the present invention, which makesinsertion into many smaller vessels difficult and poses a greatlyincreased risk of complications. Also, by having the two additionalsmaller stents connected to an end of the trunk stent, tracking into awide-angle lateral side branch may be difficult and may carry the riskof dissection of the vessel wall. Furthermore, once the device of the'071 patent is implanted, it is impossible to exchange a branch stentshould the need for a different stent size or repair of a branch stentarise.

[0009] Marcade, U.S. Pat. No. 5,676,696, discloses a bifurcated graftassembly used for 1 repairing abdominal aortic aneurysms, comprising aseries of interlocked tubes, one of which comprises a fixed angle singlebifurcated graft assembly. In contrast to the present invention, Marcadediscloses a graft, not a stent, which may not be used to treat only onevessel of a bifurcation (leaving the untreated vessel free from allobstructions). In addition, and in contrast to the present invention,the one-piece bifurcated graft portion of Marcade is uniform in size andfixed in angle, and may not be used in a vessel bifurcation where thebranch and the main vessels differ greatly in size. Also, the fixedangle will not provide as exact a fit as the variably-angled brancheddouble-stent of the invention.

[0010] U.S. Pat. No. 5,653,743 to Martin discloses a bifurcated graftassembly for use in the hypogastric and iliac arteries. In addition toteaching grafts (which are used to replace diseased vessel material) andnot stents (which, as used herein, reinforce existing vessels) Martin,in contrast to the present invention, discloses a side branch graftattached to the main graft as a single unit, requiring a larger profilethan the subject stent. Martin also claims and discloses much largercomponent sizes and methods for implantation (appropriate for thehypograstric artery, to which Martin is limited) than are operable insmaller vessels, such as those of the cardiac, coronary, renal,peripheral vascular, gastrointestinal, pulmonary, urinary orneurovascular system, or brain vessels. In addition, Martin requires twovascular access sites (FIG. 3, elements 16 and 18), whereas the deviceof the present invention requires only one access site, creating lesstrauma to the patient.

[0011] U.S. Pat. No. 5,643,340 to Nunokowa discloses a syntheticvascular bypass graft in which a side branch graft extends outward fromthe side of a second portion of the graft unit. Nunokawa, however,discloses surgically implanted extraluminal grafts and not intraluminalstents deployed by catheterization, and is therefore unrelated to thesubject of bifurcation lesions and stents, particularly stents used tointraluminally reinforce bifurcated vessels. In contrast to the presentinvention, Nunokawa is surgically implanted outside of the lumen of avessel and in fact is used to bypass damaged regions of a vesselentirely. The present invention is used to reinforce the diseasedregion, and is intraluminally implanted directly into the diseasedregion. Additionally, and unlike the present invention, the Nunokawadevice is surgically implanted and after surgical assembly of itscomponents forms a single permanently attached unit, wherein thebifurcating stent devices of the invention are deployed intraluminallyby catheter and do not require surgery or the suturing or attaching ofparts of the invention to each other or to the body vessels, allowingfor adaptation to varying branch vessel angles. Also, unlike the presentinvention, Nunokawa does not require visualization by x-ray orultrasound, as the Nunokawa device is directly seen during surgery.Lastly, the Nunokawa device cannot be deployed using catheters, is notinserted intraluminally in a compressed state and expanded while insidea vessel, and has a much larger profile than the present invention.

[0012] In general, when treating a bifurcation lesion using commerciallyavailable stents, it is important to cover the origin of the branchbecause if left uncovered, this area is prone to restenosis. In order tocover the branch origin, conventional stents inserted into the branchmust protrude into the lumen of the main artery or vessel from thebranch (which may cause thrombosis, again compromising blood flow).Another frequent complication experienced when stenting bifurcatedvessels is the narrowing or occlusion of the origin of a side branchspanned by a stent placed in the main branch. Additionally, placement ofa stent into a main vessel where the stent partially or completelyextends across the opening of a branch makes future access into suchbranch vessels difficult if not impossible. As a result, conventionalstents are often placed into the branch close to the origin, butgenerally not covering the origin of the bifurcation.

[0013] Lastly, conventional stents are difficult to visualize during andafter deployment, and in general are not readily imaged by usinglow-cost and easy methods such as x-ray or ultrasound imaging. Whilesome prior art balloon catheters (and not stents) are “marked” at theproximal and distal ends of the balloon with imageable patches, fewstents are currently available which are marked with, or which are atleast partly constructed of, a material which is imageable by currentlyknown imaging procedures commonly used when inserting the stents into avessel, such as ultrasound or x-ray imaging. The invention described inthis Application would not work with endoscopy as currently used as animaging method due to size limitations, but future advances in limitingthe size of endoscopic imaging devices may in the future make endoscopicimaging compatible with the stents of the invention.

[0014] Accordingly, there is a need for improved stent apparatuses, mostparticularly for applications within the cardiac, coronary, renal,peripheral vascular, gastrointestinal, pulmonary, urinary andneurovascular systems and the brain which 1) completely covers thebifurcation point of bifurcation vessels; 2) may be used to treatlesions in one branch of a bifurcation while preserving access to theother branch for future treatment; 3) allows for differential sizing ofthe stents in a bifurcated stent apparatus even after the main stent isimplanted; 4) may be delivered intraluminally by catheter; 5) may beused to treat bifurcation lesions in a bifurcated vessel where thebranch vessel extends from the side of the main vessel; and 6) is markedwith, or at least partly constructed of, material which is imageable bycommonly used intraluminal catheterization visualization techniquesincluding but not limited to ultrasound or x-ray.

SUMMARY OF THE INVENTION

[0015] The present invention concerns novel stent apparatuses for use intreating lesions at or near the bifurcation point in bifurcated vessels.More particularly, the invention concerns a stent apparatus with atleast one side opening which may further comprise an extendable stentportion inserted through the side opening and at least partly inregistry with the wall of the side opening. As used herein, the term“vessel” means tubular tissue within the cardiac, coronary, renal,peripheral vascular, gastrointestinal, pulmonary, urinary andneurovascular systems and the brain. Devices constructed in accordancewith the invention include, singularly or in combination, a mainexpandable stent comprising at least one substantially circular sideopening located between its proximal and distal end openings, which sideopening may further comprise a radially expandable portion extendinglaterally outward from the edges of the side opening; and an expandablebranch stent comprising proximal and distal end openings and which mayfurther comprise a contacting portion at its proximal end, and which maybe constructed to form an angularly variable branched stent apparatuswhen inserted through a side opening of the main stent. The stents ofthe invention are marked with, or at least partially constructed of, amaterial which is imageable during intraluminal catheterizationtechniques, most preferably but not limited to ultrasound and x-ray.

[0016] The stent apparatuses of the invention offers significant andnovel advantages over prior art stents in that the stents of theinvention 1) can completely cover the bifurcation point of a branchedvessel; 2) can accomodate main and branch stents of differing sizes,thus providing a better fit where the main and branch vessels are ofdifferent sizes or where the main and branch vessels are occluded todifferent degrees; 3) can fit branched vessels where the branch extendslaterally from the side of the main vessel; 4) may be used to treatlesions in one branch of a bifurcation while preserving complete accessto the other branch for future treatment; 5) may be deliveredintraluminally by catheter; and 6) are marked with, or at least partlyconstructed of, material which is imageable by commonly usedintraluminal catheterization visualization techniques including but notlimited to ultrasound or x-ray, but not endoscopy.

[0017] Thus, it is an object of the present invention to provide both adouble-stent apparatus and a single-stent apparatus, each of which maybe used to cover the origin of a bifurcation in a branched vessel.

[0018] Another object of the invention is to provide a single-stentapparatus which may be used to treat only one branch of a bifurcationlesion while leaving access to the second branch unobstructed.

[0019] Additionally, it is an object of the invention to provide a stentapparatus which is itself imageable by methods commonly used duringcatheterization such as x-ray or ultrasound.

[0020] Yet another object of the invention is to provide a bifurcatingdouble-stent device wherein the main stent and the branch stent orstents may be of different sizes.

[0021] Lastly, it is an important object of the invention to provide astent apparatus which may be used to treat bifurcated vessels where thevessel bifurcation extends laterally from the side of the main vessel.

[0022] These objects and other object advantages and features of theinvention will become better understood from the detailed description ofthe invention and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023]FIG. 1 is a schematic depiction of the double-stent apparatus ofthe present invention in which both the main stent and the branch stentare fully dilated.

[0024]FIG. 2 is a schematic depiction of the main stent of the apparatusof the invention as deployed, with the side opening in registry with avessel bifurcation point.

[0025]FIG. 3 is a schematic depiction of the branch stent of theapparatus as deployed, with the contacting portion fully expanded tocontact the origin of the bifurcated vessel.

[0026]FIG. 4 is a schematic depiction of the main stent of the apparatusdeployed within a subject vessel, after inflation of a balloon to expandthe main stent to fit the walls of the subject vessel.

[0027]FIG. 5 is a schematic depiction of the double-stent bifurcatingstent apparatus, where the main stent is deployed and showing theplacement of the branch stent apparatus prior to full deployment of thebranch stent.

[0028]FIG. 6 is a schematic depiction of the stents of the invention atvarious points during deployment within a vessel. FIG. 6a depictsinitial placement of the main stent of the bifurcating stent apparatusinto the vessel, along with the insertion of a guidewire and stabilizingcatheter for placement of the branch stent into the branch vessel of thesubject.

[0029]FIG. 6b is a schematic depiction showing the main stent of theinvention expanded by balloon expansion.

[0030]FIG. 6c is a schematic depiction of the deployment of the branchstent over the side branch guidewire, through one of the side openingsin the main stent and into the branch vessel of the subject.

[0031]FIG. 6d is a schematic depiction of the removal of the protectivesheath of the branch stent, allowing for full expansion of thecontacting portion prior to final placement and deployment.

[0032]FIG. 6e is a schematic depiction of the compressed branch stentpositioned into the branch by the catheter with the contacting portionat least partly contacting the side opening in the main stent, but priorto full expansion of the branch stent.

[0033]FIG. 6f is a schematic depiction of the fully expanded main stentand the fully positioned and expanded branch stent, where the branchstent is being dilated by inflation of a balloon.

[0034]FIG. 6g is a schematic depiction of the fully expanded bifurcatingdouble stent of the invention, positioned into the bifurcation point ina subject vessel.

[0035]FIG. 7 is a schematic depiction of the main stent with optionalexpandable portion, prior to balloon expansion of the expandableportion.

[0036]FIG. 8 is a schematic depiction of balloon expansion of theoptional expandable portion of the main stent to cover a vesselbifurcation point.

[0037]FIG. 9 is a schematic depiction of the main stent with theoptional expandable portion fully expanded to extend laterally from theside opening of the main stent.

[0038] The rectilinear matrices shown in the drawings are intended toshow the shapes of the surfaces only, and do not illustrate the actualsurface patterns or appearances of the stent apparatuses of theinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0039] The bifurcating double-stent apparatus 10 of the presentinvention comprises a generally cylindrical main stent 12 and agenerally cylindrical branch stent 15, which are shown as fully dilatedin a subject main vessel 8 and a subject branch vessel 7, as illustratedin FIG. 1.

[0040] The main stent 12 contains at least one generally circular sideopening 16 located between the proximal end 26 and the distal end 28 ofthe main stent 12 (FIG. 2), which opening is positioned over and inregistry with the opening 48 of a branch vessel in a vessel bifurcation50, as shown in FIG. 2. The stent 12 and the side opening are imagedduring imaging procedures either by constructing the stent of imageablematerials or by placing markers 56 at appropriate locations, such asaround the perimeter of the side opening 16 in the main stent 12, and atthe proximal end 26 and distal end 28 of the main stent, as illustratedin FIG. 4.

[0041] As shown in the embodiment of the invention illustrated in FIG.4, a guidewire 20 is inserted into the vessel 8 prior to insertion ofthe main stent 12, and is used to guide the main stent 12 into positionwithin the vessel 8. Prior to insertion and expansion, the main stent 12is disposed around the distal end of a catheter 48 which may include aninflatable balloon 24. The main stent/catheter apparatus is thenthreaded onto the main guidewire 20 and into the vessel 8. The mainstent 12 is radially expanded by inflation of the balloon 24 until itexpands the walls of the vessel 8, and is thus affixed into place.

[0042] In a second embodiment of the invention, the branch stentapparatus 15 of the present invention comprises a generally cylindricalstent comprising a proximal end 30 and a distal end 32, as shown in FIG.3. The proximal end 30 comprises a contacting portion, illustrated hereas extended loops 18, which contacting portion, when expanded, ispositioned within the lumen 58 of the main vessel 8 (FIG. 3) and atleast partially contacting the perimeter of the side opening 16 of themain stent 12. FIG. 4 illustrates the positioning of the main stent 12(without optional contacting portion) in the main vessel 8 as fullyexpanded by inflation of the balloon 24.

[0043] As shown in the embodiments illustrated in FIGS. 4, 5 and 7, theends of the main stent 12 and the expandable branch stent 15 and thecontacting portion 18 are visible during insertion by placing imageablemarkers 56 around the ends of the main 12 and branch 15 stents and thecontacting portion 18 and at the proximal end 30 and distal end 32 ofthe branch stent. Alternatively, the stent may be at least partiallyconstructed of material which is imageable by methods including but notlimited to ultrasound or x-ray imaging (but not endoscopic imaging).

[0044] As shown in yet another embodiment, the stents of the inventionare combined to form a bifurcating double stent as illustrated in FIGS.5 and 6. After insertion of the main stent as described above but priorto expansion of the main stent (FIG. 6a), the branch stent 15 isinserted through a side opening 16 of the main stent 12, a guidewire 36and a stabilizing catheter 44 are inserted through the side opening 16in the main stent 12, and into a branch vessel 7 (FIG. 6a). Thestabilizing catheter 44 is used to place the side opening 16 in the mainstent 12 over the bifurcation point 50 in the bifurcated vessels 7 and 8(FIG. 6a). In the embodiment depicted here, the main stent is thendeployed into position by inflation of the balloon 24 (FIG. 6b). Duringinsertion and prior to dilation of the branch stent, the branch stent 15is disposed around the distal end of a branch catheter 54 which mayoptionally include an inflatable balloon 25, and the contacting portion18 of the branch stent 15 is held in a collapsed position by aprotective sheath 34, as shown in FIG. 6c.

[0045] In the bifurcating double-stent apparatus 10 of the invention,once the main stent 12 is dilated and the stabilizing catheter 44 (asshown in FIG. 6b) is removed, the branch stent 15 is inserted over thebranch guidewire 36 and through the opening 16 of the main stent 12substantially as shown in FIG. 6c, and affixed in place by withdrawal ofthe protective sheath 34 (FIG. 6d) and insertion of the branch stent 15until it at least partially contacts the perimeter of the opening 16 ofthe main stent 12 by the expansion of the contacting portions 18 whichare positioned at the proximal end 30 of the expandable stent, as shownin FIG. 6e. The branch stent 15, once positioned in the branch vessel 7,may be then fully expanded by the balloon 25, as shown in FIG. 6f. Theangle at which the optionally expandable branch stent 15 is affixeddepends upon the vessel structure into which the bifurcating stentapparatus 10 is inserted. All catheters and guidewires are thenwithdrawn from the subject vessels, leaving the main stent 12 throughwhich the branch stent 15 is inserted into the branch vessel 7, forminga bifurcated stent 10 (FIG. 6g).

[0046] In the embodiment shown in FIGS. 7-9, the main stent 40 withexpandable portion 38 is positioned within the vessel 8 by theguidewires 20 (FIG. 7), and affixed in place by radial expansion of themain stent 40, most particularly by inflation of the balloon 25 (FIG.8). The main stent is positioned so that the opening 16 is directly overthe bifurcation point 50 in the subject vessels 7 and 8 (FIGS. 7 and 8).In order to aid such positioning, a side branch guidewire 36 and astabilizing catheter 44 (as depicted in FIG. 7) are also insertedthrough the opening 16 of the main stent 40 and through the expandableportion 38 and into the branch vessel 7 (FIG. 8).

[0047] The optional expandable portion 38 of the main stent 40 is thenexpanded radially and in an at least partially perpendicular manner tothe sides of the main stent side opening 16 (FIG. 8). In the embodimentillustrated in FIGS. 7 and 8, a balloon 25 is deployed along the sidebranch guidewire 36 through the expandable portion 38, and inflateduntil the expandable portion is fully expanded into the branch vessel 7to cover the bifurcation point 50 of the branched vessel, as illustratedin FIG. 8. In order to extend the expandable portion 38 into the branchvessel 7, a balloon 25 disposed around a branch catheter 54 which isthreaded along the side branch guidewire 36, through the main stent 40,through the opening 16 and expandable portion 38, and into the subjectbranch vessel 7 as shown in FIG. 8. The expandable portion 38 is thenextended into the branch vessel 7 by inflation of the balloon 25, whichpushes the expandable portion 38 outward radially and lateral to theside opening, into the branch vessel 7 (FIG. 8). Once all catheters andballoons are withdrawn, the expandable portion 38 is arrayed in lateralorientation to the sides of the opening 16 in the main stent 40, andsurrounding the opening 16 into the vessel branch (FIG. 9). Theguidewires 20 and 36 are then withdrawn from the main and branchvessels.

[0048] In the double stent apparatus of FIG. 5 and in the main stentwith expandable portion illustrated in FIGS. 7 and 9, the main stent aswell as the expandable portions may be constructed at least partially ofimageable material or marked with imageable markers 56 at suitablelocations, including around the perimeter of the side openings of themain stent and at the ends of the expandable portions.

[0049] When reinforcing a bifurcated vessel where both branches of thevessel require reinforcing, either 1) the single main stent with theexpandable portion is used whereby the expandable portion extends intothe vessel branch at least partly covering the origin of thebifurcation, which may be used alone or in combination with anyconventional stent; or 2) the main stent without the expandable portionand at least one branch stent with contacting portion are used, thebranch stent placed to extend through at least one side opening of themain stent into at least one branch vessel, wherein the branch stent isat least partially in registry and contacting the edge of the sideopening through which it extends. The branch stent extends laterally atvarying angles to the side opening of the main stent. When treating abifurcated vessel where the area to be treated spans the bifurcation andunobstructed access to the unstented vessel is required, the main stentmay be used either with or without the expandable portion, wherein atleast one side opening is placed over the bifurcation point.

[0050] The stent apparatus of the invention may be constructed from anynon-immunoreactive material, including but not limited to any of thematerials disclosed in the prior art stents which are incorporatedherein by reference. It is intended that the stent apparatuses of theinvention may further be at least partially constructed of, or marked atcertain points with, a material which may be imaged, most particularlybut not limited to by x-ray and ultrasound.

[0051] The stents of the invention may be deployed according to knownmethods utilizing guidewires and catheters, which are then withdrawnfrom the subject following deployment of the stents. The subject stentsmay be self-expanding to conform to the shape of the vessel in whichthey are deployed, or they may be expanded utilizing balloon catheters,or by any other method currently known or developed in the future whichis effective for expanding the stents of the invention. It iscontemplated that prior to deployment the stents will be in a collapsedstate, and will require either mechanical expansion (such as, forexample, by balloon expansion) upon deployment or, for self-expandingstents, will require that the stent be confined to the catheter untildeployment by, for instance, a retractable sheath, in which the sheathis removed during deployment and the stent self-dilated. The stents ofthe invention and the optional expandable portion of the main stent ofthe invention expand radially from their longitudinal axis, lateral tothe side opening of the main stent. Other methods of dilation of thestents of the invention may exist, or may become available in thefuture, and such methods are contemplated as being within the scope ofthis invention.

[0052] It is intended that the invention include all modifications andalterations from the disclosed embodiments that fall within the scope ofthe claims of the invention.

We claim:
 1. A generally cylindrical reinforcing stent apparatus forplacement in at least one bifurcated cardiac, coronary, renal,peripheral vascular, gastrointestinal, pulmonary, urinary orneurovascular system vessel or a vessel in the brain, comprising a mainstent having sides extending between first and second opposing ends andat least one opening being defined in a stent side.
 2. The stentapparatus of claim 1 wherein the stent comprises a self-expandingmaterial.
 3. The stent apparatus of claim 1 wherein the stent comprisesa balloon-expandable material.
 4. The stent apparatus of claim 1 whereinat least a portion of the stent is constructed of a material which isimageable.
 5. The stent apparatus of claim 1 wherein at least oneopening further comprises an expandable portion which expands radiallyfrom the perimeter of the opening.
 6. The stent apparatus of claim 1wherein the length of the stent in its compressed state is smaller than4 centimeters and the diameter of the stent in its compressed state issmaller than 2 centimeters.
 7. The stent apparatus of claim 5 whereinthe stent comprises an expandable material.
 8. The stent apparatus ofclaim 5 wherein the length of the stent in its compressed state issmaller than 4 centimeters and the diameter of the stent in itscompressed state is smaller than 2 centimeters.
 9. The stent apparatusof claim 5 wherein at least a portion of the stent is constructed of amaterial which is imageable by x-ray or ultrasound.
 10. The stentapparatus of claim 1 further comprising a second stent disposed at leastpartly within the main stent and having sides extending between proximaland distal opposing ends, wherein the second sent is a branch stent andthe second branch stent being moveable and adapted to be extended in anangularly flexible fashion through at least one of said side openings ofsaid main stent and at least partially contacting the perimeter of saidside opening.
 11. The stent apparatus of claim 10 wherein the secondstent additionally comprises a contacting portion located at itsproximal end, which contacting portion at least partially contacts theedges of said main stent side opening.
 12. The stent apparatus of claim10 wherein the stents comprise an expandable material.
 13. The stentapparatus of claim 10 wherein the stents comprise a balloon-expandablematerial.
 14. The stent apparatus of claim 10 wherein at least a portionof the stents are constructed of a material which is imageable.
 15. Thestent apparatus of claim 10 wherein the length of the stent apparatus inits compressed state is smaller than 4 centimeters and the diameter ofthe stent apparatus in its compressed state is smaller than 2centimeters.
 16. A bifurcating double-stent reinforcing apparatus forintraluminal placement by catheter within a bifurcated vessel comprisingfirst and second generally cylindrical stents, wherein the second stentis a branch stent and is located at least partly within the first stent,and having sides in each stent extending between first and secondopposing ends, and at least one opening being defined in a side of thefirst stent and the second branch stent being moveable and adapted to beextended through at least one of said side openings of said first stentand at least partially contacting the perimeter of said side opening andextending into a vessel branch, said first and second stents each beingconstructed from a material which allows said stents to expand toconform to the shape of the subject vessel.
 17. The stent apparatus ofclaim 16 wherein the second branch stent additionally comprises aproximal end and an opposing distal end, wherein the proximal endadditionally comprises a contacting portion, which contacting portion isat least partially in contact with the perimeter of said first stentside opening.
 18. The stent apparatus of claim 16 wherein the firststent further comprises an expandable portion which expands in avariably angled lateral manner from the perimeter of the first stentside opening.
 19. The stent apparatus of claim 16 wherein the first andsecond stents comprise a self-expanding material.
 20. The stentapparatus of claim 16 wherein the stents comprise a balloon-expandablematerial.
 21. The stent apparatus of claim 16 wherein at least a portionof the stents are constructed of a material which is imageable.
 22. Thestent apparatus of claim 16 wherein at least a portion of the stents aremarked with a material which is imageable.
 23. The stent apparatus ofclaim 16 wherein the length of the stent appartus in its compressedstate is smaller than 4 centimeters and the diameter of the stentapparatus in its compressed state is smaller than 2 centimeters.
 24. Agenerally cylindrical bifurcated reinforcing stent apparatus forplacement in at least one bifurcated cardiac, coronary, renal,peripheral vascular, gastrointestinal, pulmonary, urinary orneurovascular system vessel or a vessel in the brain, comprising aradially expandable stent with sides extending between first and secondopposing ends and at least one opening being defined in at least onestent side, and wherein at least one side opening further comprises anexpandable portion which expands radially from the edges of an opening,and further wherein at least a portion of the stent is constructed of amaterial which is imageable and wherein the length of the stent in itscompressed state is smaller than 4 centimeters and the diameter of thestent in its compressed state is smaller than 2 centimeters.
 25. Abifurcating double-stent reinforcing apparatus for intraluminalplacement by catheter within a bifurcated cardiac, coronary, renal,peripheral vascular, gastrointestinal, pulmonary, urinary orneurovascular system vessel or a vessel in the brain comprising a firststent with sides extending between first and second opposing ends and atleast one opening being defined in a stent side and a second generallycylindrical stent, wherein the first stent may optionally furthercomprise an expandable portion which expands radially from the edge ofone opening of said first stent side, and wherein the second stent is abranch stent and comprises a proximal end and an opposing distal end,wherein the proximal end may optionally comprise a contacting portionwhich at least partly contacts the edges of said first stent sideopening and which is located at least partly within the first stent, andthe second stent being moveable and adapted to be extended through atleast one of said side openings of said first stent in an angularlyflexible fashion, said first and second stents each being constructedfrom a material which allows said stents to expand to conform to theshape of the subject vessel, wherein at least a portion of the stentapparatus is constructed of a material which is imageable and whereinthe length of the stent apparatus in its compressed state is smallerthan 4 centimeters and the diameter of the stent in its compressed stateis smaller than 2 centimeters.